The present invention relates to hybrid topographical and chemical pre-patterns for directed self-assembly of block copolymers, and more specifically, to pre-patterns supporting perpendicular orientation of self-assembled domain patterns over regions of the pre-pattern having different etch characteristics.
The directed self-assembly (DSA) of block copolymers (BCPs) is a promising resolution enhancement technology to extend patterning. Chemoepitaxy, a form of DSA, has been demonstrated to reliably generate dense grating and hexagonal arrays from sparse chemical pre-patterns comprising a directing region (alignment conferring non-neutral region with preferential affinity to one domain) and a non-directing region (neutral region) supporting perpendicular orientation of BCP domains. In chemoepitaxy for a block copolymer having a bulk periodicity (pitch) of Lo (“L nought”), the width of the alignment conferring regions can be approximately 0.5 Lo (i.e., 0.5 times Lo) or approximately 1.5 Lo.
For example, in a report of systematic study of chemoepitaxy using a chemical pre-pattern having a pitch of 3 Lo for 3× density multiplication (i.e., 3 times density multiplication), where the pre-pattern was made from crosslinked polystyrene as the directing region and a neutral material as the non-directing region that supports perpendicular orientation, good DSA was only achieved when the width of the alignment conferring region of the pre-pattern was 0.4 Lo to 0.8 Lo, or about 1.3 Lo (Detcheverry, et al., Macromolecules, 2010, vol 43, pages 3446-3454; Rincon, et al., “Determination of Critical Parameters for Control of Directed Self-Assembly of Block Copolymers Using Frequency Multiplication, 2012 Report of SRC Annual Review, University of Chicago). If the width of alignment conferring region was outside this range of values, good DSA was not obtained. In addition, if the alignment conferring region was larger than 2 Lo, good DSA was not obtained. Instead, flipped domains and defects were observed.
Many patterning applications demand complex customization of dense DSA patterns. Recently the customizations of dense DSA arrays using a separate cut layer were implemented in two different approaches: customization before DSA layer formation (“cut-first”), and customization after DSA layer formation (“cut-last”). Cut-first schemes using buried customization levels under the DSA guiding layer have been demonstrated (Sayan, et al., “Directed Self-Assembly Process Integration—Fin Patterning Approaches and Challenges”, Proc. of SPIE, Advances in Patterning Materials and Processes XXXI, 2014, Vol. 9051, 90510M). Cut-last customization of 42 nm pitch line-space DSA patterns after DSA with separate mask have also been demonstrated (Liu, et. al., “Towards electrical testable SOI devices using Directed Self-Assembly for fin formation”, Proc. SPIE 9049, Alternative Lithographic Technologies VI, 904909, 2014). However, as the pitch of the DSA pattern becomes smaller, customization of the DSA pattern becomes more challenging because of the tight overlay budget.
A need exists for multi-layer pre-patterns supporting self-aligned customization of perpendicularly oriented DSA domain patterns over regions possessing different wetting properties and etch characteristics with wide design spaces, for generation of self-aligned customized transfer patterns that minimize the need to align separate cut layers.